Circuit breaker



Oct. 24, 1944. K. w. WILCKENS CIRCUIT BREAKER 2 Sheets-Sheet 1 Filed April 6, 1939 Oct. 24, 1944. w w c s 2,360,922

CIRCUIT BREAKER Filed April 6, 1939 2 Sheets-Sheet 2' 70 F A3 A? IN VENTOR.

Y Karl: W Mlaliens A RNEY.

Patented Oct. 24, 1944 CIRCUIT BREAKER Kurt W. Wilckens, Trenton, N. J., assignor to Heinemann Circuit Breaker Company, Trenton, N. 1., a corporation of New Jersey Application April 6, 1939, Serial N0. 266,316

(01. zoo-s9) 10 Claims.

' pactness and simplicity of such devices.

Leading objects of my invention are to overcome the tendency of switch contacts to bond together on a short circuit after having been roughened on a previous short circuit, .and to thereby avoid the need for constructing contacts of, or facing them with, expensive non-bonding materials; to provide a conducting switch bar of rigid material normally strongly biased toward open position but making, when closed, a yielding engagement with its complementary contact so as to insure perfect engagement of the contact surfaces without the use of a resilient conducting blade; to provide a latched toggle mechanism through which the switch may be manually operated and which is readily unlatched by electro-responsive mechanism to effect automatic opening of the switch; and to provide a. frame upon which all of the movable breaker elements may be assembled as a unit, which serves as a stop for the switch bar, as a magnetic pole piece of the electro-responsive tripping mechanism, as a support and shield for an electro-magnetic coil, and as a physical and magnetic partition in a breaker housing from which flames resulting from short-circuit arcing are effectively vented through vents between the hollow base and hollow cap of the housing.

In a preferred embodiment of my invention, a hollow, rectangular insulated housing, containing a fixed contact and blow-out plates, has its walls internally grooved to provide a seat or slidewai for a switching and tripping unit which may be held in place in the housing by a single screw.

This unit comprises an L-shaped frame having lugs projecting laterally from one leg thereof for engagement in the body grooves, a pair of ears extending from each of the legs of the frame and forming bearings for a switching bar and switch-throwing and tripping mechanisms, and a tube mounted in and extending through the leg of the frame transverse to the leg engaged in the body grooves and having wound thereon an electro-magnetic coil which is largely shielded by the frame.

The switch bar is preferably a single rigid zigzag piece connected with the frame by a rocking and sliding joint comprising a slot in the bar forming an elongated bearing for a pin or shaft journalled in elongated bearings in the ears of the frame-leg in which the tube is mounted. The longitudinal center lines of the hearings in the bar and in the ears are disposed diagonally to one another throughout the throw of the switch bar from its open position to its closed position. Thus the mounting of the switch bar is such that its base may be rocked about the axis of the pin and moved bodily relatively to the axis of the pin parallel to the tube axis and transverse to the tube axis. These movements of the switch bar permit rocking and wiping movements of the contact section thereof relative to the fixed contact in the normal operation of the switch and permit the rocking of the base of the switch bar and a splitting movement of the contact section thereof relative to the fixed contact should the contacting surfaces become bonded together. By causing the latter movement to occur -abruptly or by a snap action, the engagement of the pin against the ends of its slots at the end of its throw produces a shock or jar tending to break any bond that may have occurred between the contacting faces.

A coiled spring mounted on the frame normally biases the fulcrumed end or base section of the switch bar downwardly and outwardly with respect to the fixed contact and strongly biases the contact section of the switch bar away from such fixed contact. The frame limits the outer movement of the bar so that the spring need not be entirely unfiexed when the bar is fully open and hence may be so wound as to efiect a strong thrust without being excessively rigid.

The switch bar is manually operable, through pivoted latching links, by a handle fulcrumed on the second pair of cars bent from the frame. To automatically open the breaker, on overload, the latched links are tripped by a spring-biased and electro-re'sponsive L-shaped lever fulcrumed on the frame-ears carrying the handle; the rocking of this lever being limited by the frame or a stop carried thereby. I

Instead of making the switch bar of a single rigid piece connected with the frame by a rocking and sliding joint and biased by a single spring, the bar may consist of a rigid base section connected with the frame by a rocking joint and a rigid contact section connected with the base section by a rocking and sliding joint; each of the sections being biased by an independent spring. The switch bar is thereby movable as a unit on its frame fulcrum to close or open the breaker and the contact section and base section may rock and slide relatively to one another to permit the contact section of the bar to yieldingly engage the fixed contact and permit the base section of the bar to impart a blow and splitting movement to the contact section to insure the separation of the contacts.

My improvements are primarily applicable to automatic electro-responsive circuit breakers and particularly to those which are immune to temperature changes and have magnetic trip mechanism which permit continuous flow of current, when the breaker is closed, up to slight harmless overloads of, say, of rated capacity, which efiect instantaneous tripping on short circuits or heavy overloads of, say, 1000% of rated capacity and which have an inverted time delay between these limits which will effect tripping within a time inverse to the extent of overload so that the larger the overload the more quickly the breaker will open. Certain advantages of my improvements are, however, applicable to circuit breakers having instantaneous electro-magnetic tripping devices or director supplementary thermal tripping devices, or even to circuit breakers devoid of automatic tripping means.

The characteristic features and advantages of my improvements will further appear from the following description and the accompanying drawings in illustration thereof.

In the drawings, Fig. 1 is a sectional view through a circuit breaker housing showing in side elevation the operating parts of a preferred embodiment of my improvements with the switch bar open; Fig. 2 is a part sectional side elevation of the breaker shown in Fig. 1 with the switch bar closed, the view being from the opposite side from that shown in Fig. 1; Fig. 3 is a fragmentary front elevation of part of the breaker mechanism and the casing with its cap removed; Fig. 4 is a transverse sectional view taken on the line 4-4 of Fig. 1; Fig. 5 is an exploded view of parts of the mechanism shown in Figs. 1 and 2; Fig. 6 is a fragmentary, somewhat diagrammatic, side elevation of the switch bar shown in closed position; Fig. .7 is a view similar to Fig. 6 showing the positions of the parts in breaking a bond between the surfaces of the switch electrode; Fig. 8 is a view similar to Fig. 7 with the switch bar in open position; Fig. 9 is a perspective View of the latching toggle; Fig. 10 is a perspective view, partly in section, of a circuit breaker embodying a modified form of my improvements; Fig. 11 is a longitudinal sectional view through the casing of the circuit breaker shown in Fig. 10 with the switch bar closed; Fig. 12 is a longitudinal sectional view of the circuit breaker shown in Fig. 10 with the switch bar open and taken from the opposite side from Fig. 11; Fig. 13 is an exploded view of parts of the circuit breaker shown in Figs. 10 to 12; Fig. 14 is a detached, somewhat diagrammatic, side elevation showing a further modified switch bar shown in closed position; Fig. 15 is a view similar to Fig. 14 but showing the parts in the position occupied in breaking a bond between switch contact surfaces; and Fig. 16 is a view similar to Fig. 15 with the switch bar in open position.

In the embodiment of my invention illustrated in Figs. 1 to 9 of the drawings, a blank of magnetic metal is bent to form an integral frame comprising an L-shaped body having legs I and 2 disposed at right angles to one another, a pair of parallel L-shaped ears 3 extending transversely to the leg I from the edges thereof near the angle of the body, a pair of parallel slanting ears 4 extending transversely to the leg 2 from the edges thereof near its outer extremity, and a pair of lugs 5 projecting laterally from the leg 2 between the ears 3 and 4. The ears 3 contain slots 6 forming elongated bearings for a pintlev 1 movable therein substantially parallel to the leg 2. The pintle 1 forms a fulcrum for a zigzag switch bar 8 containing an elongated inclined slot 9 in the base thereof for the passage of the pintle.

A pintle I0 is fixed in apertures II in the ears 3 below the slots 6 and has wound thereon the coils of a spring I2 having its ends anchored beneath the lugs 5 of the leg 2. The spring I2 has an intermediate yoke-like section I2 bearing against the inclined surface 8' of the switch bar and normally biases the bar downwardly and outwardly toward the lower right hand corner of the cover (Fig. 1) so that the pintle 1 lies in the outer extremities of the slots 6 (viz., in

the slot extremities nearest the leg I) and the upper extremities of the slots 9 when the switch is open, as shown in Fig. 8. But a suitable component of forces on the switch bar 8 tends to shift the pintle I toward the extremities of the slots 6 furthest from the leg I, and a suitable component of forces on the switch bar 8 tends to shift it upward so that the pintle 1 lies in the lower extremities of the slots 9. The longitudinal center lines of the slots 6 and 9 are diagonally transverse to one another in the operative positions of the switch blade so that movement of the pintle relative to one pair of slots may take place to a certain extent without movement of the pintle in the other pair of slots if the upper end of the switch is free to move, but the resultant of movements of the pintle relative to both pairs of slots is a shifting of the fulcrum on which the bar rocks inward and upward or outward and downward relative to the fixed electrode.

A sheet metal blank is bent to form a link I3 comprising cheeks I4 and I4 connected by a cross-head I5 having an adjustable tongue I8 projecting therefrom. A pintle II passes through apertures I8 in the cheeks I4 and I4 and through the aperture I9 in the switch blade 8 to pivotally connect the link I3 with the switch bladeabove the upper extremity of the spring member I2. The link I3 is pivotally connected with an end of a link 20 by a pintle 2| passing through apertures 22 and 23 in the respective members, and the opposite end of the link 20 is pivotally connected with a handle -24 having a shaft 25 journalled in bearings 265m the ears 4.

The link 20 has atooth 21 adapted to abut against the convex surface of the leg 28' of a yoke-shaped pin 28 journalled in the cheeks I4 and I4 to latch the links I3 and 20 rigidly together. Preferably either the yoke 28 or the link I3 is made of non-magnetizable material. A spring 29, having one end anchored to the link I3 is wound about the leg 28 to bias this leg so that its head 28" bears against the cheek I4 so as to maintain the fiat surface 28" of the leg 28' between the cheeks I4, I4. The free end of the spring 29 bears against the leg 28a of the yoke so as to bias it toward one end of a slot 30 in the cheek I4 and rock the leg 28' so that a convex face thereof normally lies in the path of the tooth 21. The flat face 28" is formed by recessi ng the leg 28' sufficiently to permit the passage of the tooth 21 past the leg 28' when the face 28" is brought into line with the tooth by rocking the leg 28a to the upper extremity of the slot 30.

Force is transmitted between the handle 24 and the switch blade 8 through the pivotally connected link 20 and I3 when the toggle formed thereby is rendered rigid by the engagement of the tooth 21 with a convex surface of the leg 28, but when the leg 28a is rocked to disengage the leg 28' from the path of the tooth the toggle is tripped to permit the spring I2 to operate the switch bar 8.

The rocking of the yoke 28 is preferably effected by the engagement of the leg 28a by electro-responsive tripping means such as an L- shaped lever 3i having ears II Journalled on a pieces 2 and 46' to break the circuit without pin 32' seated in the bearings 33 of the ears 4. The lever 3| has its arm 34 normally biased toward the leg 2 and away from the pin 2611 by a coiled spring I! wound on the pin 32 and having one end engaging the lever arm and the other end adjustably engaged in a serrated member 36 fixed to the frame leg 4 and having a tall 31 which may be bent to limit the outward movement of the lever arm 34' to a desired degree.

The handle 24 is normally biased into position for straightening the toggle by a spring wound on the pin 25 and having one end anchored in the handle 24 and the other end bearing against the pin 32.

The lever arm 34 is preferably made of magnetically permeable material so as to form an armature attracted by the poles of an electromagnet preferably consisting of a non -magnetizable tube 44 secured in an aperture in the leg I and having wound thereon, between the insulating discs 4| and 42, a coil 43 for creating a magnetic flux upon the passage of electric current therethrough. One end of the coil is connected through a flexible looped pigtail 43' with the switch blade 6 and the other end of the coil may have connected therewith a. terminal 43".

The tube 46 contains a magnetically permeable cylindrical core 44 which is moved by a magnetic flux of sufllcient intensity, against the biasing action of a coiled spring 45, into direct contact with a magnetic pole piece 46 forming an end closure for one end of the tube 40. The periphery of the core 44 is recessed to permit the passage of the forepart of the core through the spring 45 against the pole piece 46. The frame in which the tube is mounted forms the other pole of the electro-magnet and the end of the leg 2 thereof is so aligned with the pole 'piece 46 as to coact therewith in attracting the armature 34'.

The core 44 is of a length substantially equal to the distance between the inner face of the pole piece 46 and the plane of the pole piece formed by the leg I at the opposite end of the coil so that a highly permeable magnetic circuit is established when the core 44 contacts the inner face of the pole piece 46, thereby creating sufllcient magnetic attraction to draw the armature 34 against the pole pieces 2 and 46, and rock the arm 34 and the yoke 26.

When normal current or current not in excess of 125% of normal capacity is flowing through the coil 43, the magnetic flux created is insufllcient to overcome the biasing action of the spring 45 to move the core 44 against the pole piece 46, and the pole pieces 2 and 46 exert too little magnetic attraction to rock the armature 34 when the core 44 is retracted. Upon the occurrence of a momentary overload, not exceeding ten times rated capacity, the dashpot action of the fluid, such as air or oil, in the tube 46, prevents the movement of the core 44 against the pole piece 46 and the armature 34 is not attracted. But if an overload, exceeding say 125% of capacity, is long continued, the fluid seeps gradually past thecore 44 and this core is moved forward slowly by'the abnormal flux until it contacts the pole piece 46. This so closes the magnetic circuit that the armature 34' is pulled against the pole pieces 2 and 46 and operates the mechanism to break the circuit. In the event of a short circuit or excessive overload, exceeding say ten times normal capacity, the armature 34' is instantaneously attracted against the pole awaiting any movement of the core 44.

A unit so assembled may be mounted in the insulating housing 50 whose walls are provided with grooves or slideways 60' for the engagement of the ears 6 on the leg 2. The unit may be secured in position by a single counter-sunk screw 6| threaded into an aperture in theleg l. A binding screw 52 holds the terminal 43" against displacement and secures a line wire thereto.

' The housing preferably has embedded in the 'wall thereof a conducting strip 64 having a. proiecting terminal 56 provided with a binding screw 56. The inner end of the conducting strip is connected through a counter-sunk screw 61 with a flxed contact consisting of an apertured conducting strip wound around an insulated core 66 and havinga slanting terminal member 6i forming a contact surface complementary to the contact surface 62 0:! the switch bar 8. The .core 60 has magnetic blow-out plates 63 fixed to the ends thereof and insulated from the switch members by the asbestos and fibre housing 64 and 65 supported by the core 66.

The base of the housing is provided with outwardly beveled longitudinal edges 66 which are slightly spaced from the square edges 61 of a cover 68 having a transverse partition 69.

shielding the handle slot 69' from arcs resulting from a short circuit. Flames and gases generated or expanded by arcing wit hin the housing are deflected by the edges of the cover, projecting over the bevel 66 of the base, harmlessly through the slots between the cover and case. The cover leaves the terminal 43" exposed for the attachment of a conductor.

The maximum air gap between the armature 34' and pole pieces 2 and 46 is so fixed by adjusting the tongue 31, and the tension of the spring 35 on the armature 34' is so adjusted by moving the tail of the spring in the serrated member 36, that the armature 34' is not attracted by the pole pieces 2 and 46 on the passage of current less than, say, 125% of rated current, through the coil, but the armature 34' is attracted by the pole pieces 2 and 46 on the passage of over 125% rated current if the end of the core 44 directly contacts the pole piece 46 and its opposite end substantially registers with the leg I so as to provide a magnetic circuit which is 'metallically closed over most of its length. The pole pieces 2 and 46 will attract the armature 34' on the passage of say ten times rated current or over even though the core 44 be fully retracted. The attraction of the armature 34' by the pole pieces 2 and 46 on the flow of current between 125% and 1000% of rated current will depend upon the length of the air gap in the magnetic circuit between the pole piece 46 and the core 44 and the position of the core 44 will in turn be dependent upon the duration of the overflow current. The spring 45 will normally maintain the core retracted on the flow of current up to approximately 125% of rated current, and the fluid, such as air or oil, in the tube will retard the rectilineal movement of the core 44 on the flow of current in excess of so that there will be a lag in the operation of the breaker after excess current begins to flow therethrough dependent upon the rate of current flowing.

The closing of the magnetic circuit by bringing the core 44 into direct engagement with the pole piece 46 and into close juxtaposition with the pole piece formed by the leg I results in an effective pull of the pole pieces 2 and 46 on the armature 34 at 125% of rated capacity substantially equal to the pull created by the flow of 1000% of rated current with the core 44 fully retracted, or a ratio of approximatey 8 to 1. In other words, the closing of the magnetic circuit by the cores coaction with the two pole pieces permits the operation of the breaker "with oneeighth the ampere turns required to operate the breaker in the absence of the core or with the core retracted.

The opening of circuit breakers under short circuit conditions causing heavy arcing tends to form small beads or burrs on the faces of metallic contacts and if the breaker is reclosed during the maintenance or recurrence of short circuit conditions such beads or burrs may be melted by the passage of heavy current therethrough in the instant before the contacts make fully engagement. Contacts are thereby sometimes instantaneously so bonded or soldered together as to resist a direct pull of a biasing spring tending to open the circuit breaker. My improvements minimize such bonding tendencies by giving a slight sliding or wiping movement to the bar contact and break any bond which forms by imparting a jar or shock and a shearing movement from the spring to the blade when the toegle is broken or released.

This will more clearly appear from a consideration of the positions of the pin 1 in Figs. 1,

2., 6, 7 and 8. When the breaker is open (Figs. 1 and 8), the loop l2 of the spring I2 biases the bar 8 toward the right and downwardly so that the pin 1 lies adjacent to the ends of the slots 6 nearest the leg I and adjacent to the upper ends'of the slots 9. When the handle 24 is turned to rock the bar 8 on its fulcrum toward closing position, the force transmitted through the pintle I'I turns the bar on the pin I and shifts the pin 1 toward the ends of the slots 6 furthest from the leg I. The bar contact face 62 engages the fixed contact face 6| before the throw of the handle 24 is completed, and since the fixed contact member 6| prevents further inward movement of the contact end of the bar, the continued application of force from the handle 24 through the pintle II rocks and shifts the bar 8 so that its slotted lower end moves inwardly and upwardly relatively to the pin 1 until the pin 1 lies in the lower parts of the slots 9. The contact face 62 is thereby given a wiping movement over the face GI and at the completion of the movement is biased yieldingly against the contactGI.

When the breaker is opened either by tripping the toggle latch or by rocking the handle 24, the spring section l2 tends to shift the pin 1 toward the ends of the slots 6 nearest the leg I and to shift the bar downward so as to move the upper endsof the slots 9 toward the pin I thereby causing the face 62 to wipe and smooth the face 6|. If the surface 62 has bonded to the surface 6|, the bar 8 is turned by the spring I2 on the point of bond as a center and the movements of the bar applies a splitting or shearing and wiping force to separate the bonded surfaces 62 and BI and the jar or shock resulting from the impact of the pin 1 against the ends of the slots 6 nearest the leg I is transmitted through the rigid bar to jolt loose any remaining bond between the contact faces. The bar 8 is thereupon rocked on the pin 1 to its fully open position.

In Figs. 10 to 13 I have shown a further embodiment of my invention in which like numbered parts are the same as those heretofore described butdn which certain details of construction, including the switch bar, unlatching mechanism and easing, have been somewhat modified.

In this embodiment of my invention, the switch bar includes a base section 8a pivoted on a pintle la joumalled in circular bearings Ba of the ears 3 of the frame member I, and a contact section comprising a channeled member 8b having ears containing elongated slots 8d through which pass the pintle II connecting the link I3 with the base section 8a. The end of the member 8b has riveted thereto a contact member 62a. A spring I2a, wound on the pintle la, has its ends anchored under the bosses 5 and a looped section [211' tending to bias the switch bar toward open position.

A spring I2a" fixed to the breaker housing tends to bias the contact section 8b relative to the base section 811.

The throw of the handle 24 and the links I3 and 20 connecting it with the switch bar are so proportioned that when the pin I1 is at the inner ends of the elongated slots 8d viz., nearest the member 81), and the tail of the member 8b is flush with the member 8a, the contact 62a engages the face of the contact Gla before the throw of the handle 24 is completed. This causes the member 81) to rock on its fulcrum I'I against the biasin action of the coiled leaf spring l2a" mounted on the wall of the casing. When the handle 24 is thrown or the links are unlatched to open the breaker, if the contacts should be bonded, the spring I2a' throws the arm 8a outward away from the member 8b so that the pintle I'I strikes sharply against the outer ends of the slots 8d, thereby imparting a jar or shock to the contact 62a tending to break its bond with the contact 6Ia, and this jar is supplemented by the splitting or shearing force imparted to the contact section 8b by the actions of the springs l2a' and I2a tending to turn it on the point of bonding as a center.

Instead of mounting an adjustable stop 3| for the armature 34a" upon the arm 4 of the bracket, a coil 31a of thermostatic metal may be attached to an elongation of the fixed shaft 32 with its free end bearing against the armature 34a" so that upon a predetermined increase in temperature of the breaker, the armature 34a" is moved into the attracting field of the electro-magnetic pull of the poles 2 and 46 regardless of the position of the core 44. The arm 34a of the armature may be split longitudinally to provide a readily bendable finger 34b for engagement with the arm 2 to adjustably limit the outward movement of the armature arm 34a".

In this embodiment of my invention, the contact GIa forms a part of a V-loop constituting an integral part of a conducting bar 54a extending forwardly along the inner wall of the breaker housing and terminating in a contact 55a bent normally to the bar 54a and fixed to a lateral extension of the casing by a binding screw 56a. If desired, the V-loop may be held firmly against the wall ofthe casing by a screw 51a so that the V-loop will provide ample support for an insulated core 60a on the ends of which are mounted the blow-out plates 83a and the flbre and asbestos shields 65a and 64a.

The switch bar is connected through the looped pigtail 43' with one end of the electro-magnetic coil 43 wound on the tube 40 and having its other end connected with the terminal contact 43a" which is secured by a binding screw 52a to a lateral projection on the casing. If desired, a portion of the current may be shunted through the thermostatic member an; in the usual manner.

The casing preferably consists of a hollow moulded base containing a chamber H housing the bulk of the breaker mechanism which is covered by a hollow cap 12 containing an opening 13 for the passage of the handle 24. The base 10 has an integral crenelated extension at the side thereof providing a seat 14 for the terminal contact 55a. a seat 15 for the terminal contact 43a, a recessed seat 15 for a ground contact l1 and apertured recessed walls 18 and 19 through which mounting screws may be passed to support the breaker casing without objectionably decreasin the non-conductor distance between terminals or conducting members.

As shown in Figs. 14 to 16, there may be substituted for the coiled leaf spring l2a", a coiled spring l2b' sleeved on the headed pin 120 which is fixed to the arm 80. and passes through an aperture in the member 8d, but this construction is less desirable than the embodiments of my invention above described because of the tendency of the spring I2b to counteract the action of the spring Na in opening the breaker when the contact 62a is bonded to the contact 6| a.

Having described my invention, I claim:

1. A circuit breaker comprising a frame containing elongated bearings, a shaft slidable in said bearings, a switch bar having elongated bearings and rockingly and slidably mounted on said shaft, and a contact complementary to said bar, said frame bearings and end bearings having longitudinal center lines disposed transversely to one another and permitting bar movements in directions transverse to one another.

2. A circuit breaker comprising a pair 'of bearings containing elongated slideways, a switch bar containing an elongated slideway, a pintle movable in the slideways of said bearings and in handle and an L-shaped lever fulcrumed on the other pair of brackets, and links connected with the bar and handle transmitting thrust between said switch bar and handle and means rendering such links ineffective by the rocking of said lever.

5. A circuit breaker comprising an L-shaped frame, a switch bar and handle fulcrumed on said frame said switch bar being fulcrumed adjacent to the bend of said frame and said handle being fulcrumed adjacent to an end of said frame, links for transmitting thrust between said bar and handle, and electro-responsive mechanism supported by said frame adjacent to the handle-end thereof for rendering said links ineffective, said mechanismv including a coil lying on the opposite side of said frame from said links.

6. A circuit breaker comprising an L-shaped frame, a switch bar and handle fulcrumed on said frame said switch bar being fulcrumed adjacent to the bend of said frame and said handle being fulcrumed adjacent to an end of said frame, links for transmitting thrust between said bar and handle, and electro-responsive mechanism supported by said frame for rendering said links ineffective, said mechanism including a lever mounted on said frame.

7. A circuit breaker comprising a housing containing an electrode and an operating unit including a frame seated in said housing and having a leg parallel with and adjacent to the back wall of the housing and a leg extending forwardly transversely thereto, a switch bar complementary to said electrode, and electro-responsive mechanism for controlling said switch bar and shielded by said frame from arcing between said bar and electrode.

8. A circuit breaker comprising a housing having a hollow base with an electrode and blowout 3. In a circuit breaker having a switch blade and an operating handle, a toggle connecting said blade and handle and including a pair of Pivotally connected links, one of said links having a tooth and the other of said links having a shiftable member engaged by said tooth to lock said links in one position of said member, and means for moving said member out of engagement withsaid tooth to break said'toggle, one of said links containing a slot limiting the throw of said member.

4. Ina circuit breaker, a supporting structure and an operating unit comprising an integral L- shaped frame having arms disposed substantially 3% right angles to one another, each of said arms having a pair of brackets projecting therefrom said brackets forming fulcrums, a switch bar fulcrumed on onepair of brackets, an operating plates at One end thereof, a magnetizable frame at the other end thereof, means shielded by said frame for magnetizing said frame, a switch bar complementary to said electrode and fulcrumed on said frame, and a cover for said base and forming therewith flame vents between said blowout plates and frame.

9. A circuit breaker comprising a housing having a hollow base with beveled side edges and containing an electrode, a switch bar in said housing complementary to said electrode, means for manually and automatically operating said switch bar and a cover for said base having edges forming flame deflectors adjacent to said beveled edges, and said edges of said base and cover I forming flame vents.

10.A circuit breaker embodying-a magnetizable frame having transverse legs, a non-magnetic tube projecting through one leg and along the other leg of said frame, a magnetizable closure for one end of said tube, said closure having a face aligned with a face of said frame, a core in said tube movable by magnetic flux into direct contact with said closure, said core extending to the plane of said first named leg when directly engaging said closure, a spring biasing said core away from said closure, a flux-generating coil on said tube between said first named leg and said closure, an armature having a fulcrum offset from both said faces and movable by flux emanating therefrom toward said faces, and a switch controlled by said armature.

KURT W. WILCKENS. 

